This happens only with very few emails which seem to follow some pattern which I cannot recognize.

The behavior in Kerios Webmail is even more strange: Here, in the Drafts Folder, said emails don't have any Recipient. When I enter the recipient here and send the email, no problems occur. However, these changes in the Drafts folder don't syncronize to Outlook.

I tried reindexing and deleting and reconfiguring the account in Outlook. Some problem with Drafts still exisit, e.g. if I delete a draft in Outlook, it still exists in Webmail. If I create a new draft in Webmail however, it gets syncronized correctly to Outlook.

The message should be created in Sent Items folder. Folder GUID can be found in status.fld of the folder, so first check if it is identical. But it would be strange that you don't have access to your Sent Items folder, so probably it's other folder.

Hi Pavel.
I just compared the folders GUIDs. The GUID in the error message is NOT the Sent Items folders but the INBOX folder of some other Account which is also set up at that computer.
How can that happen? Why would Outlook want to save a sent message in some other accounts Inbox? Is there any way to change that behaviour?

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